This invention provides a method for treatment and prophylaxis of diabetes comprising administering conjugated linoleic acid to subjects suspected of suffering from or at risk of developing diabetes.
Diabetes mellitus is a chronic metabolic disorder characterized by a high concentration of glucose in blood (hyperglycemia) which is a result of insulin deficiency and/or insulin resistance. Diabetes is a common disease in humans, with more than 50 million cases worldwide. There are two main forms of diabetes, insulin-dependent diabetes mellitus (e.g., Type I diabetes) and non-insulin dependent diabetes mellitus (e.g., Type II diabetes).
Insulin is the main form of treatment of Type I diabetes and has to be administrated parenterally (e.g., by injection). Today, most of the insulin in clinical use is produced recombinantly. Type II diabetes can be treated with various oral anti-hyperglycemic agents like biguanidines (e.g., metformin), sulphonylurea compounds such as tolbutamide, chlorpropamide, glipizid and glibenclamide, and acarbose (i.e., an alpha-glucosidase inhibitor). Very mild forms of diabetes mellitus (Type II) can often be kept under control by the patient without use of drugs by selection of correct diet (e.g., intake of limited amounts of carbohydrates), bodyweight reduction for obese patients, increased exercise and reduction of stress.
Anti-diabetic drugs only provide symptomatic relief and do not cure the disease. Thus, affected patients usually undergo treatment for the rest of their lives. Anti-diabetic drugs have several unwanted effects such as stimulation of appetite resulting in gain of body weight, hypoglycemia, gastrointestinal upsets, allergic skin reactions, bone marrow damage and cardiovascular effects. (See, e.g., Godman and Gilman""s xe2x80x9cThe Pharmacologocal Basis of Therapeuticsxe2x80x9d, 9th edition and xe2x80x9cH. P. Rand et al., Pharmacology 1995xe2x80x9d, Churchill Livingstone).
Research continues in the development of improved drugs and treatment regimens. Of particular interest is the development of drugs with increased safety and efficacy. Ongoing concerns include the detrimental interactions of current anti-diabetic drugs with other medications in common use (e.g., anti-inflammatory agents), development of drug resistance and/or tolerance, and patient compliance with prescribed treatment regimes.
What is needed are safe and effective compounds for treating diabetes that lack significant side effects and can be consumed as part of the normal diet.
An important challenge in modern medicine is to devise safe and effective methods of treating diabetes. It is therefore an object of the present invention to provide a safe method of treating Type I and Type II diabetes through the use of a naturally occurring substance, conjugated linoleic acid (CLA). Accordingly, the present invention provides methods for the use of CLA in treatment and prophylaxis of diabetes.
In one embodiment of the present invention, methods are provided for treating diabetes in human patients suffering from diabetes that comprises administering a safe and therapeutically effective amount of conjugated linoleic acid. In some embodiments, the patients suffer from Type I diabetes, while in other embodiments, patients suffer from Type II diabetes. In some preferred embodiments, a safe and effective amount is sufficient to reduce the percentage of glycoslylated hemoglobin (HbAIC) in the patient""s blood. In some embodiments, the method of treatment comprises: a) providing i) a safe and therapeutically effective amount of conjugated linoleic acid; and ii) a patient suffering from diabetes; and b) administering said safe and therapeutically effective amount of conjugated linoleic acid to said diabetic patient. In other embodiments, the method of treatment comprises providing: i) a patient at risk for diabetes, and ii) a therapeutic composition comprising a safe and effective amount of conjugated linoleic acid; and b) prophylactically administering the therapeutic composition to said patient.
In some embodiments of the invention, the conjugated linoleic acid administered to patients is a mixture of octadecadienoic acid isomers selected from the group of cis-9, trans-11; cis-9, cis-11; trans-9, cis-11; trans-9, trans-11; cis-10, cis-10, trans-12; trans-10, cis-12; trans-10, trans-12 octadecadienoic acid. In other embodiments, the conjugated linoleic acid administered to patients contains less than 5% of minor isomers of conjugated linoleic acid. In still other embodiments, the minor isomer is c11,t13; t11,c13; t11,t13; or c11,c13 octadecadienoic acid. In a particularly preferred embodiment, the conjugated linoleic acid contains less than 1% of minor isomers of conjugated linoleic acid. In other embodiments, the conjugated linoleic acid further comprises an ester or triglyceride. In still other embodiments, the conjugated linoleic acid further comprises greater than about 55% t10,c12 octadecadienoic acid.
In other embodiments of the present invention, the conjugated linoleic acid comprises a daily dosage of about 0.05 to 40 grams. In some particularly preferred embodiments, the conjugated linoleic acid comprises a daily dosage of about 1 to 5 grams. In some embodiments, the conjugated linoleic acid is administered orally in a gel capsule. In other embodiments, the conjugated linoleic acid is provided as a supplement to a low carbohydrate diet. In still other embodiments, the conjugated linoleic acid is provided in a food product (e.g., prepared food or drink).
In some embodiments, the conjugated linoleic acid is co-administered with an anti-hyperglycemia agent. In other embodiments, the anti-hyperglycemia agent is selected from the group consisting of insulin, metformin, chorplopamide, glipizid, glibenclamide and acarbose.
The following definitions are provided to make the invention be more easily understood:
As used herein, xe2x80x9cdiabetesxe2x80x9d refers to any disease characterized by a high concentration of glucose in blood (hyperglycemia) and includes, but is not limited to, both Type I diabetes mellitus and Type II diabetes mellitus.
As used herein, xe2x80x9cType I diabetesxe2x80x9d refers to any insulin dependent diabetes disease.
As used herein, xe2x80x9cType II diabetesxe2x80x9d refers to any non-insulin diabetes disease.
As used herein, xe2x80x9cpatient at risk for diabetesxe2x80x9d refers to any person having risk factors known in the art for Type I diabetes (e.g., family history, descent (African or hispanic), etc.) or Type II diabetes (e.g., family history, age (over 45), obesity, previous diagnosis of impaired glucose tolerance, physical inactivity, etc.).
As used herein, xe2x80x9cconjugated linoleic acidxe2x80x9d or xe2x80x9cCLAxe2x80x9d refers to any conjugated linoleic acid or octadecadienoic acid. It is intended that this term encompass and indicate all positional and geometric isomers of linoleic acid with two conjugated carbon-carbon double bonds any place in the molecule. CLA differs from ordinary linoleic acid in that ordinary linoleic acid has double bonds at carbon atoms 9 and 12. Examples of CLA include cis- and trans isomers (xe2x80x9cE/Z isomersxe2x80x9d) of the following positional isomers: 2,4-octadecadienoic acid, 4,6-octadecadienoic acid, 6,8 -octadecadienoic acid, 7,9 - octadecadienoic acid, 8,10- octadecadienoic acid, 9,11-octadecadienoic acid and 10,12 octadecadienoic acid, 11, 13 octadecadienoic acid. As used herein, CLA encompasses a single isomer, a selected mixture of two or more isomers, and a non-selected mixture of isomers obtained from natural sources, as well as synthetic and semisynthetic CLA. As used herein, CLA further encompasses free fatty acid(s) of CLA, physiologically acceptable salts of CLA, and esters with physiologically acceptable, preferably naturally occurring, alcohols ( e.g., ethanol and glycerol).
As used herein, it is intended that xe2x80x9ctriglyceridesxe2x80x9d of CLA contain an isomer of CLA at any or all of three positions on the triglyceride backbone. Methods for the synthesis of triglycerides containing CLA are taught in PCT Application US99/05806, incorporated herein by reference.
As used herein, it is intended that xe2x80x9cestersxe2x80x9d of CLA include any CLA isomer bound through an ester linkage to an alcohol or any other chemical group. Methods for the synthesis of esters containing CLA are taught in PCT Application US99/05806, incorporated herein by reference.
It is intended that xe2x80x9cminor isomersxe2x80x9d of CLA include, but are not limited to c11,t13; t11,c13; t11,t13; and c11,c13 octadecadienoic acid. xe2x80x9cPrepared food productxe2x80x9d means any pre-packaged food approved for human consumption.
As used herein, xe2x80x9ccxe2x80x9d encompasses a chemical bond in the cis orientation, and xe2x80x9ctxe2x80x9d refers to a chemical bond in the trans orientation. If a positional isomer of CLA is designated without a xe2x80x9ccxe2x80x9d or a xe2x80x9ctxe2x80x9d, then that designation includes all four possible isomers. For example, 10,12 octadecadienoic acid encompasses c10,t12; t10,c12; t10,t12; and c10,c12 octadecadienoic acid.
This invention provides a method for treatment and prophylaxis of diabetes comprising administering conjugated linoleic acid to subjects suspected of suffering from or at risk of Developing diabetes. Insulin is commonly used to treat diabetes and acts by regulating carbohydrate metabolism. In addition to carbohydrate metabolism, insulin also has several effects on the metabolism of fat and fatty acids that are of concern in patients with diabetes. For example, insulin increases the synthesis of fatty acids and triglycerides in adipose tissue. U.S. Pat. No. 5,496,735 (herein incorporated by reference) discloses a method of determination of patient risk for diabetes based on lipid fatty acid in serum.
There are several reports that document an increased amount of conjugated fat compounds in the tissues of diabetic patients. Inouye et al. have shown a significant increase in the ratio of CLA to linoleic acid in human diabetic erythrocytes compared with control erythrocytes. (Inouye et al., Clin. Chim. Acta., 287:163-72 (1998)). An increased CLA (9,11 isomer) to linoleic acid ratio in diabetic rats has also been demonstrated. (al-Zuhav et al., Pharmacol. Res., 38:59-64 (1998)). Another report on oxidative stress and metabolic control in non-insulin dependent diabetes mellitus (NIDDM) indicated that hypoglycemic agents substantially lower concentration of cis, trans and trans conjugates dienes in low-density lipoprotein esters and triglycerides. (Singh et al., Indian J. Biochem. Biol., 512:17 (1998)). The concentrations of these dienes were found to be significantly higher in subjects with NIDDM than in subjects with normal glucose tolerance. Gumbirer et al. have shown that mono-unsaturated fatty acid enriched hypocaloric diets potentiate the beneficial effects of weight loss and improve cardiovascular risk factors in obese patients with type II diabetes. (Gumbirer et al., Diabetes Care, 21:9-15 (1998)). Additional reports indicate that increased levels of conjugated dienes occur in blood plasma in patients with diabetes. (See, e.g., Santini et al., Diabetes, 46:1853 (1997); Zhang, et al., Arterioscler. Thromb. Vasc. Bid, 18:1140-48 (1998); Khajanachumpol, et al., J. Med. Assoc. Thai., 80:372-77 (1998); Leonthardt, et al., Clin. Chim. Acta., 254:173-86 (1996); and Dimitiradis, J. Am. Geriatric. Soc., 39:571-4 (1991)). In contrast, Colier et aL, Diabetic Med., 5:747-9 indicate that the concentration of CLA is reduced in insulin-dependent diabetic patients. Thus, there are conflicting reports in the literature regarding the CLA levels in diabetic patients.
Fatty acid metabolites of linoleic acid and linolenic acid have been suggested for use in the treatment of diabetes, as well as several other severe diseases. (See, e.g., U.S. Pat. Nos. 4,681,896; 4,806,569; and 4,868,212, incorporated herein by reference). However, the use of conjugated linoleic acids is not described in these patents. U.S. Pat. No. 5,034,415 (each incorporated herein by reference) discloses a method for treating diabetes mellitus comprising administering isomers of eicosapentaenoic acid (EPA) or 22:6 omega -3 docosahexaenoic acid (DHA). U.S. Pat. No. 4,472,432 (herein incorporated by reference) discloses a method of treating diabetes comprising administration of xe2x80x9calphaxe2x80x9d and xe2x80x9cbetaxe2x80x9d unsaturated fatty acids and Houseknecht et al., Biochem. Biophys. Res. Commun., 244:678-82 (1998) indicate that CLA is able to normalize impaired tolerance and improve hyperinsulinemia in an animal model (i.e., pre-diabetic Zucker diabetic rats).
Conjugated linoleic acid has been identified in meat and dairy products (Chin et al., J. Food Comp. Anal., 5:185-197 (1992)). CLA has several unique properties when used as a food additive or dietary supplement. U.S. Pat. No. 5,554,646 (herein incorporated by reference) discloses the use of CLA to reduce the percentage of fat in relation to total body mass. Other publications describe a variety of physiological effects caused by CLA including reduction in body fat, changes in energy metabolism, and changes in cardiovascular health indicators. (See, e.g., Wast, et al., Am. J. Physiol., 275:R667-72 (1998), and Lee et al., Atherosclerosis, 108, 19-25 (1994).
U.S. Pat. No. 5,428,072 (incorporated herein by reference) discloses the use of CLA for increasing the efficiency of feed conversion in animals, which results in more non-fat tissue being formed in relation to weight gain. U.S. Pat. Nos. 5,430,066 and 5,585,400 (both incorporated herein by reference) disclose the use of CLA to prevent weight loss due to immune stimulation and to treat immune hypersensitivity. CLA also has anticarcinogenic activity. (See, e.g., Belury, Nut. Rev., 53(4):83-9 (1995); Santoli, Anticancer Res., 18:1429-34 (1998); Thompson, Cancer Res., 57:5067-72 (1997); Liu et al., Lipids, 32:725-30 (1997); Durgam et al., Cancer Lett., 116:121-30 (1997); Ip et al., Carcinogenesis, 18:755-9 (1997); and Wong, Anticancer Res., 17:987-93 (1997).
The mechanism by which CLA mediates these effects is not known, and indeed an understanding of the mechanism is not necessary in order to use the invention. Nonetheless, some biochemical models involving fat partitioning and shifts in fatty acid precursor mediated synthesis of end product prostaglandins and leukotrienes have been proposed. For example, it is known that CLA is taken up in triglycerides and phospholipids, and deposited in fat stores. The precise structure and distribution of these lipids is not known. Nor is it known whether there is a competitive incorporation amongst two or more isomers, or a preferential deposition of certain isomers in some lipid species over others. Such an understanding is not required in order to use the present invention.
In preferred embodiments, the CLA of the present invention comprises a mixture of one or all of the isomers of octadecadienoic acid including the cis-9, trans-11; cis-9, cis-11; trans-9, cis-11; trans-9, trans-11; cis-10, cis-12; cis-10, trans-12; trans-10, cis-12; and trans-10, trans-12 isomers. The rearrangement of the double bonds of linoleic acid to conjugated positions has been shown to occur during treatment with catalysts such as nickel or alkali at high temperatures, and during autooxidation. Theoretically, eight possible geometric isomers of 9,11 and 10,12 octadecadienoic acid (i.e., c9,c11; c9,t11; t9,c11; t9,t11; c10,c12; c10,t12; t10,c12 and t10,t12) would form from the isomerization of c9,c12-octadecadienoic acid.
A general mechanism for the isomerization of linoleic acid was described by Cowan (Cowen, JAOCS, 72:492-99 (1950)). Although an understanding of the mechanism is not required for the practice of the present invention, it is believed that the double bond is polarized by the result of a collision with an activating catalyst. The polarized carbon atom and its adjoining carbon are then free to rotate and the forces are such as to make the deficient carbon atom essentially planar. When the system reacts to relieve these forces set up as a result of the collision, both cis and trans isomers are formed. The formation of certain isomers of CLA is thermodynamically favored. This is due to the co-planar characteristics of the five carbon atoms around the conjugated double bond and a spatial conflict of the resonance radical.
Although an understanding of this mechanism is not required for the practice of the present invention, the relatively higher distribution of 9,11 and 10,12 isomers apparently results from the further stabilization of the c9,t11or t10,c12 geometric isomers. The cis-9,trans-11 and trans-10, cis-12 isomers are thought to have the most biological activity. Therefore, in preferred embodiments, these isomers may be used in a purified form, or in CLA compositions containing high ratios of these isomers. Most preferably, the CLA composition used in the present methods is TONALIN(trademark)CLA 80 (Natural Nutrition, Norway). In addition, methods for manufacturing CLA 80 are provided in Example 2 (i.e., low temperature nonaqueous alkali isomerization) and an alternative method of manufacturing another preferred CLA composition is provided in Example 3 (i.e., isomerization with alkali alcoholate in the presence of a monohydric low molecular weight alcohol). Both methods provide for the production of CLA predominantly comprising the c9,t11- and t10,c12- isomers, with low levels of 8,10-,11,13- and trans-trans isomers. In preferred embodiments of the present invention, CLA mixtures contain less than about 5% of minor CLA isomers; while in particularly preferred embodiments, the present invention utilizes CLA with less than about 1% of minor CLA isomers. Preferred isomers in the CLA mixtures include 9,11 -octadecadienonic acid, 10,12- octadecadienoic acid, most preferably the c9,t11 and t10,c12 isomers. In other preferred embodiments, the mixture contains greater than about 50% t10,c12 isomer. In other particularly preferred embodiments, the mixture contains greater than about 55% t10,c12 isomer. In a particularly preferred embodiment, the mixture contains greater than about 60% t10,c12 isomer. It is contemplated that in some embodiments, supplementation of the mixture derived from isomerization of linoleic acid with purified or synthesized t10,c12 isomer may be necessary to achieve these percentages.
In a preferred embodiment of the present invention, a safe and therapeutically effective amount of CLA is orally administered to a human with diabetes. The use of CLA for these indications is desirable because CLA is a non-toxic, naturally occurring food ingredient. CLA is not classified as a drug and may be consumed as a part of a normal diet and finds use as a part of everyday nutrition. In a preferred embodiment, the CLA may be used as a fatty acid supplement for the low carbohydrate diets often prescribed for diabetic patients.
A xe2x80x9ctherapeutically effective amountxe2x80x9d of CLA is the amount of CLA that, when ingested in purified form or as food supplement, results in an improvement of Type II diabetes symptoms without impairing or interfering with proper nutrition. In particularly preferred embodiments, the administration of CLA results in no detrimental effects in patients. In some embodiments, about 0.05 to 40 grams of CLA may be administered per day, preferably about 1 to 10 grams per day may be administered, and most preferably about 3.0 grams per day may be administered. In general, the amount of CLA administered is not critical, as long as it is enough to be therapeutically effective. The amounts of CLA deemed therapeutically effective are those which result in a measurable decrease in HbAIC (i.e., glycosylated hemoglobin) when administered over a three month period or longer. HbAIC is useful as an index of hyperglycemic stress, and is elevated in patients with poorly managed diabetes. The glycation of HbAIC is a non-enzymatic, post-translational event linked to elevated levels of glucose in the blood. HbAIC levels may be determined as is known in the art by HPLC. (See, e.g., Inonye et al., Clin. Chim. Acta., 295:163-72 (1998); Gabbay, N. Engl. J. Med., 295:443-4 (1976); Koenig et al., N. Engl. J. Med., 295:417-20 (1976)).
It is contemplated that there will be some variation in effectiveness due to differences among individuals in physiological and biochemical parameters (e.g., body weight and basal metabolism), exercise, and other aspects (e.g., diet). It is contemplated that individuals beginning treatment will be given a 3.0 gram dose for an initial two month period, and then, if no reduction serum glucose is experienced, gradually increase the CLA dose up to about 10 grams per day.
The present invention also contemplates the use of derivatives of CLA. For example, CLA may be free or bound through ester linkages or provided in the form of an oil containing CLA triglycerides. In these embodiments, the triglycerides may be partially or wholly comprised of CLA attached to a glycerol backbone. The CLA may also preferably be provided as a methylester or ethylester. Furthermore, the CLA may be in the form of a non-toxic salt, such as a potassium or sodium salt (e.g., a salt formed by reacting chemically equivalent amounts of the free acids with an alkali hydroxide at a pH of about 8 to 9).
In one preferred embodiment, administration is oral. The CLA may be formulated with suitable carriers such as starch, sucrose or lactose in tablets, pills, dragees, capsules, solutions, liquids, slurries, suspensions and emulsions. The CLA may be provided in aqueous solution, oily solution, as a powder, or in any of the other forms discussed above. The tablet or capsule of the present invention may be coated with an enteric coating which dissolves at a pH of about 6.0 to 7.0. A suitable enteric coating which dissolves in the small intestine but not in the stomach is cellulose acetate phthalate. In a preferred formulation, the CLA is provided as soft gelatin capsules containing 750 mg 80% CLA (TONALIN(trademark)). In another preferred embodiment, the CLA is provided as a powder contained in a capsule. The CLA may 5 also be provided by any of a number of other routes, including, but not limited to, intravenous, intramuscular, intra-arterial, intramedullary, intrathecal, intraventricular, transdermal, subcutaneous, intraperitoneal, intranasal, enteral, topical, sublingual or rectal means. Further details on techniques for formulation for and administration and administration may be found in the latest edition of Remington""s Pharmaceutical Sciences (Maack Publishing Co., Easton, Pa.).
An effective amount of CLA may also be provided as a supplement in various prepared food products and drinks. For the purposes of this application, prepared food product means any natural, processed, diet or non-diet food product to which CLA has been added. The CLA may be added in the form of free fatty acids or as an oil containing partial or whole triglycerides of CLA. Therefore, CLA may be directly incorporated into various prepared food products, including, but not limited to diet drinks, diet bars, supplements, prepared frozen meals, candy, snack products (e.g., chips), prepared meat products, milk, cheese, yogurt and any other fat or oil containing foods.
In some preferred embodiments, CLA is used in combination with anti-hyperglycemic agents. Examples of such agents with which CLA can be combined include insulin, metformin, chorplopamide, glipizid, glibenclamide and/or acarbose. In still other embodiments, CLA may be used in combination with vanadium compounds, chromium compounds, lipoic acid, AGE inhibitors/breakers or other compounds with known positive effect on relieving the symptoms associated with diabetes.
CLA is susceptible to oxidation. Therefore, it is desirable to package CLA for human use with suitable antioxidants such as lecithin, tocopherols, ascorbate, ascorbyl palmitate or spice extracts such as rosemary extract.